Sewing machine drive



May 5, 1942. l., c. MARsAc ET Al.

SEWING* MACHINE DRIVE Filed Feb.4 19. 1941 il a INVENTORS LEONA/PD C. /VARJAC DAV/D A. 619/455367? Patented May 5, 1942 SEWING MACHINE DRIVE Leonard C. Marsac, Cranford, and David A. Graesser, Elizabeth, N. J., assignors to The Singer Manufacturing Company,

Elizabeth,

N. J., a corporation of New Jersey` Application February 19, 1341, Serial No. 379,588

2 Claims.

This invention relates to motor-driven sewing machines, and more particularly to variable speed sewing machines which are driven by small individual motors permanently connected in driving relation therewith. These driving motors are usually of the high-speed series wound type and their speed is controlled by a manually actuated rheostat connected in series therewith.

This type of sewing machine is most commonly used in the home where a light compact sewing outfit having a moderate operating speed is required. Such a high-speed motor is therefore usually provided with a small driving pulley which is at all times operatively connected, by

means of a belt, to a larger driven pulley mounted f on the sewing machine. Thus a proper speed reduction is effected between the motor and the sewing machine. y

Unfortunately this type of machine has had the undesirable characteristic of running unevenly in the low-speed range. This characteristic is highly objectionable as it is within the low-speed range that this type machine is often used in y order to perform such work as embroidering, darning and hemstitching. This type of work is best accomplished with a sewing machine producing about fifty to seventy-five stitches per minute as compared to a regular sewing speed of about twelve hundred stitches per minute.

Some prior motor-driven sewing machines have been proposed, with little or no success, to overcome the above noted objectionable characteristic by the use of a heavier balance-wheel on the main shaft, or by the use of gears in lieu of the driving belt, or by generally strengthening the machine itself. Such expediente make for a heavy, slow running and costly machine.

It is therefore, an object of the present invention to provide an inexpensive, practical and light-weight family sewing machine including a motor-drive that will deliver a steady ilow of power to the machine at all speeds and, particularly, in the low speed range used, for eX- ample, in embroidering and darning operations.

It is known that a machine of the above described type will operate smoothly at low speeds if a balance-wheel of relatively heavy weight is applied to the sewing machine main-shaft. However, such a machine is found to be sluggish in operation and too great a starting load is thereby applied to the small driving motor. The present applicants have drastically reduced the weight of the main shaft balance-wheel and have mounted a relatively small, light-weight balance-wheel upon the motor shaft. The weight of the motor 55 balance-wheel is much less than the weight which was removed from the above mentioned machine balance-wheel.

The applicants have found that by providing a small balance-wheel on the motor-shaft and by reducing the weight of the main-shaft balancewheel, a steady flow of power will be available at all speeds, thus permitting a fine speed control at all times and particularly while in the low-speed range. In addition, it has been found that by removing weight'from the main-shaft balancewheel, slippage between the motor-driving pulley and the sewing machine driving belt is reduced to a marked extent. In the present machine the weight of the combined main shaft balancewheel and driven pulley is reduced to a minimum by constructing the same of cast aluminum, light gauge sheet-metal or some similar material. This unit in the present machine now functions primarily, not as a balance-wheel, but as a handwheel, it being understood that hand-wheels on family sewing machines are required by their operators so that the machine may be turned over by hand, as in raising the needle for removal of work.

To more concretely illustrate the results of the present invention, the following figures are cited. It must be understood however that the invention is not limited in any manner by these figures and that they merely illustrate one specific form in which the invention may be applied.

The sewing machine herein illustrated is a Singer No. 221 class machine of the light-weight portable type weighing about eleven pounds and utilizing', prior to the application of the present invention, a main-shaft balanceand pulleywheel weighing one. pound and a half. Upon the application of the present invention, this old balanceand pulley-wheel was replaced by a combined hand-wheel and belt-pulley weighing ten ounces, and a seven ounce iiy-wheel was mounted upon the motor-shaft. Thus it was found that not only were the slow-speed running qualities of the machine improved but an overall weight saving of seven ounces was made, such a saving representing four percent of the total weight of the prior machine.

The invention both in structure and in operation, as well as additional objects thereof, will be best understood from the following description taken in conjunction with the accompanying drawing in which:

Fig. 1 is a rear elevation of the improved sewing machine, a portion of the bracket-arm being broken away to show the operating elements thereof.

Fig. 2 is an end elevation looking from the left of Fig. 1.

Figf 3 is a disassembled perspective view of a portion of the driving means.

Fig. 4 is a vertical section View of the assembled unit shown in Fig. 3.

Referring more specically to the drawing, the invention is disclosed in connection with a sewing machine comprising a frame including a hollow base I carrying a standard 2 from which extends an overhanging bracket-arm 3 terminating in the hollow-head 4.

Fixed to the base I is a, motor-supporting bracket 5 formed with a channel which slidably receives the rectangular shaped boss 1 carried by the frame of the driving motor` 8. The boss 'I is adjustably ixed to the bracket 5 by means of a bolt 9 which extends through a slot I0 in the bracket 5 and is threaded into the boss I. Thus from the above it will be understood that the motor 8 may be raised or lowered on its support.

Journaled lengthwise within the overhanging bracket-arm 3 is the sewing machine rotary main-shaft II which actuates the usual needlebar mechanism located within the hollow head A. Mounted upon the outboard end of the mainshaft II is an extremely light-weight combined handand pulley-wheel I2 which is driven from the motor 8 by means of the V-belt I3. The shaft II is connected in the usual manner to drive the needle-bar mechanism and the loop-taker actuating shaft I4 is driven through the gears I5, vertical shaft I 6 and gears I'I.

The loop-taker actuating shaft I4 is disposed within the hollowr base I, as, are the rock-shafts IB and I9 which impart to the feed-bar 20, carrying a feed-dog 2|, the usual feed-lift andfeed advance and return movements. The rock-shafts I3 and I9 are actuated by the pitmans 22 and 23, respectively, the pitmans receiving their motion from the usual feed-actuating eccentrics 2li carried by the main-shaft I I.

The motor 8 is provided with end-caps 25 and 26 and journaled within saidmotor is the usual motor-shaft 21 which is disposed in substantially parallel relation with said main-shaft I I. Upon the outboard end of the motor-shaft 2l', which projects through end-cap 25, is mounted a driving pulley 28 secured thereto by means of setscrews 29. The outer endv of the driving pulley 28 is provided with a countersunk hole 30 which receives the screw 3l. As best shown in Figs. 3 andA 4, the end of the motor-shaft 21 is tapped to receive the pulley-screw 3l, thus securing the pulley 28 upon the shaft 21. A hub 32 is provided on the pulley 28 upon which is mounted a flywheel 33 secured thereto by means of setscrews 34.

The driving pulley 28 is operatively connected with the hand and driven pulley I2 by means of the above noted V-belt I3. The diameters of the driving pulley 28 and the driven pulley I2 are of such proportion that they eect a reduction in speed of about three or four to one.

In order to effectively control the speed of the motor 8 a foot-controlled rheostat 3l is connected in series therewith by means of an electrical conductor 35. A lead-in electrical conductor 35, connectedy with the motor 8, is adapted to be connected to a suitable source of electrical energy as by means of a connector-plug 38.

Thus from the above description it may be understood that the sewing machine main-shaft I I is actuated by the motor-shaft 2l through the speed-reducing unit comprising the driving pulley 28, the V-belt I3 and the driven pulley I2.

Having thus set forth the nature of the invention, what we claim herein is:

l. A motor driving attachment for sewing machines having a frame, a rotary shaft journaled within said frame, and a driven pulley and handwheel mounted upon said rotary shaft, comprising, an electric motor having end-caps and a motor-shaft, said motor-shaft extending through one of said end-caps, a driving pulley having an elongated' hub mounted upon the outboard end of said motor-shaft, said driving pulley adapted to be operatively connected to said' driven pulley by means of, a belt, and a balance-wheel having at least one set-screw, said balancedyheel being secured upon said elongated hub.

2. In a sewing machine having a frame including a bed and a gooseneck, a rotary shaft journaled within said frame, a driven pulley and hand-wheel mounted upon said rotary shaft, an electric motor mounted upon said frame and having end-caps and a motor-shaft, said motor shaft extending through one of said end caps, a driving pulley mounted upon the outboard end of said motor-shaft, and a belt connecting said driving and driven pulleys; the improvement which consists in the provision of an elongated hub-portion integral with said driving pulley, and a balancewheel having at least one set-screw, said balancewheel being secured upon said elongated hub between said driving pulley and said end-cap by means of said set-screw.

LEONARD C. MABSAC. DAVID A. GRAESSER. 

